Core Web Vitals Report Example

In this post we discuss the differences between Lab Data, Field Data & Origin Summary data which are necessary in order to analyse Core Web Vitals data to improve user experience and organic rankings.

Google’s Core Web Vitals metrics have been designed to help companies see how their websites compare to their competitors in term of page experience for users. They provide interesting data that will allow companies to see what their website might be doing wrong, and what it might be doing right in terms of how users experience the site. Since these metrics also impact organic search rankings and visibility it is important a website passes the test both to drive traffic to the website and then to turn those visitors into customers.

Core Web Vitals are essentially 3 metrics to assess how fast a web page loads, how quickly it becomes visually stable and how quicky a visitor can interact with it e.g. by clicking a button.

You can read and download our Core Web Vitals Guide here.

And here is a summary of the 3 metrics:

Core Web Vitals Metrics - Overview

When a website has a low score in any of the 3 metrics then there is a good chance that there are issues with the website that a business should be addressing. Fixing these issues can help boost rankings on search engines. Perhaps even more importantly, it can also provide any visitors to a site with a user experience that is better than on competitors’ websites. 

The 3 Core Web Vitals metrics became part of the algorithm that Google uses for rankings in June 2021. Therefore, if you haven’t already had a good look at your Core Web Vitals it really is time to do so. Google applies a traffic light score for each of the 3 metrics depending on different values and units as shown below:

Core Web Vitals Technical Details

It is simple to check the metrics in Google Search Console(see our guide for more details) but Google also reports more detailed data and it is important to understand how to interpret that data to ensure any issues are fully resolved.

Lab Data, Field Data & Origin Summary Explained

If you are looking to assess your Core Web Vitals, then you need to ensure that you have the best tools for the job. Google Search Console and PageSpeed insights are great for assessing the performance of your website against the Core Web Vitals tests. But it is important that you understand exactly what you are doing. This is because some of the terminology that is used in these tools can be confusing. 

One of the more popular questions that many people who are about to undertake a Core Web Vitals assessment ask is “what are the differences between field data, lab data and origin summary?”

Read on as we look to explain what each of these means and more importantly what the differences are. 

What is field data?

Field data is essentially used to help a company understand they type of audience that they might be reaching. These data are recorded by browsers as a result of real-world usage that takes place on any given website. 

Field data is necessary because it is this that Google uses to create what is referred to as the “page experience ranking factor.” The information collected under the bracket of field data is normally better than that related to any lab data scores for exactly the same page on any website. As a grouping, the information that is gathered under the heading of field data should be more stable over time. A location or IP address, for example, doesn’t change. You can refine the information that you collect, but the core elements should remain the same. 

Web browsers need to have permission if they are going to transmit any type of scores. Field data is collected and then sent so it can be used by PSI, any tools dedicated to Core Web Vitals or by those who are involved in the writing of JavaScrips related to Core Web Vitals for websites. 

How is field data generated?

Field data is generated by everyday users in the following ways:

  • Through the use of different devices – mobile phones, computers, tablets
  • Through different internet speeds
  • As a result of different locations
  • In PageSpeed Insights it is only generated for the URL that is being tested
  • It is based on the Chrome User Experience Report (CrUX) – this means it is not live data, but an average of that collected over the last 28 days
  • For a website overall to be rated “good” in regards to the performance of a particular Core Web Vitals metric, Google has decided that 75% of the page’s views, as a minimum, need to be good.

Thus, in an area with powerful devices and high internet speed, you would expect to see field data performance being better than lab data.

What is lab data?

Lab data is defined by the data that is accumulated when you load a web page in an environment that is controlled and has a predefined set of device and network conditions. Soit is a synthetic environment. The developer tool Lighthouse is usually used to report lab data. A Lab test is used to control the largest number of factors possible. This ensures that where possible the results will be consistent and can be reproduced from one run to the next.

It is important to understand that lab data is powered by LightHouse technology. This implements what is termed “mobile throttling” to determine what the performance would be on a slow device or slow network (e.g. a 3G connection). The CPU that is used by LightHouse is one that is usually slower than that available to the average user but essentially represents a worst-case scenario when it comes to page speed and user experience. 

Google Chrome Developer Tools can be used to run LightHouse and it can be run from any Chrome browser. A Lighthouse report will show the settings that have been used in any particular experiment.

What is origin summary?

The third dataset that might be used to analyse issues with Core Web Vitals metrics is origin summary. Origin summary is similar to field data but is a representation of the average performance of all pages on a website, or domain, rather than just a single page. 

In order to create the origin summary Google analyses all page views over a 28 day period and if 75% of the total page views of the site pass a particular Core Web Vitals metric then the site is deemed to have attained a “good” performance in respect of that metric. 

When you look in Google Search Console, the Core Web Vital charts that are available show the history of any origin summary.

Which dataset should you be most concerned about?

In order to judge your page or the entirety of your website Google will use the field data from the Chrome User Experience Report. However, bear in mind that for some websites with low traffic Google will not record field data and origin data so you may have to rely on Lab data to implement any necessary fixes.

We recommended that the origin summary date (if available) is monitored in the reports from PageSpeed Insights but it is also fine to use lab data as a consistent data source for testing and monitoring improvements. 

Search Console and Page Speed Insights are both free Google tools that provide valuable data that can significantly help a business improve the user experience on their website in order to attract more visitors and convert visitors to customers. Learning how and when to use them to best effect is essential for any company competing in organic search. 

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